Daiken ASHP

[DOIGAN]

Hi,

Hopefully someone can help.

At this time of year my monobloc struggles to heat my house. The temperatures here in Orkney are actually mild compared with the rest of the UK so ambient temperature should not be the issue.

 

The first screenshot shows the sensor readings when the system is producing hot water to 48 degrees. As you can see the PHE temp is good.

 

Now the second screenshot shows the temperature sensors when the system is producing heating, as you can see the PHE temperature is really low and the pipework is cool to the touch. Due to these low temperatures circulating around the pipework I think this is why my rooms are not heating up. In the summer it is better. Does anyone know why the PHE temperature is so low when heating is requested?

 

Thanks

 

[ProDave]

There are usually separate settings to set the water temperature for DHW and heating mode separately.

 

Running the heating temperature at the lowest temperature it will work at will give the greatest efficiency for a number of reasons.  If it is heating the house okay at this temperature then leave it alone, but if it struggles then find the setting and increase it a bit.

 

Most units also have an option of weather compensation so will automatically increase the heating temperature as the outside air gets colder.

 

Do you have the manual and do you understand how to change system parameters?

[DOIGAN]

Hi Prodave,

 

Pretty converse with this system now as I have been playing around with it for a year now, I have always had issues with it and am convinced it isn't working properly, I have had 3 different engineers out but none seem to offer any options. My neighbour has the same unit and his PHE reads 36 degrees when heating on, this makes more sense as by the time you factor heat loss the circulating temp will be high 20's which is what you want. I have my leaving temp set at 34 degrees but system will not go that high.

 

Unfortunately the system does not heat the house, my thermostats are set at 19 degrees and none reach that high, even after system running 12 hours or more, it does use electricity though ?

[ProDave]

25 minutes ago, DOIGAN said:

Hi Prodave,

 

Pretty converse with this system now as I have been playing around with it for a year now, I have always had issues with it and am convinced it isn't working properly, I have had 3 different engineers out but none seem to offer any options. My neighbour has the same unit and his PHE reads 36 degrees when heating on, this makes more sense as by the time you factor heat loss the circulating temp will be high 20's which is what you want. I have my leaving temp set at 34 degrees but system will not go that high.

 

Unfortunately the system does not heat the house, my thermostats are set at 19 degrees and none reach that high, even after system running 12 hours or more, it does use electricity though ?

Then that sounds like the ASHP may be too small for the house if it is failing to heat the UFH up to the set temperature.

 

To test that theory, if you are not using all the rooms, turn the room thermostats down in some rooms so you are say heating only half the house and see if it then reaches the set temperature.

 

How big is the house?  What levels of insulation? Do you have any heat calculations e.g SAP? what size is the HP?

[DOIGAN]

3 bed Scotframe 120 m square

7kw/h heat pump. Daikin Altherma EDLQ07CAV3

 

 

 

Results summary
Results summary - New dwelling as built - Worksheet version 9.90 - Energy Design Tools SAP 2009 v4.2
Regulations: Scottish Technical Handbook
SAP 2009 = B 81.09 | EI 2009 = B 82.56 | DER = 20.16 | TER = 28.45 | FEE = 61.20
Heat demand kWh: space 5671 water space 2495
PCDF revision number: 357 (30 April 2014) External Definitions revision number: 4.5 (1 March 2011)

 

Hopefully these SAP results mean something to you Dave.

[ProDave]

9 minutes ago, DOIGAN said:

3 bed Scotframe 120 m square

7kw/h heat pump. Daikin Altherma EDLQ07CAV3

 

 

 

Results summary
Results summary - New dwelling as built - Worksheet version 9.90 - Energy Design Tools SAP 2009 v4.2
Regulations: Scottish Technical Handbook
SAP 2009 = B 81.09 | EI 2009 = B 82.56 | DER = 20.16 | TER = 28.45 | FEE = 61.20
Heat demand kWh: space 5671 water space 2495
PCDF revision number: 357 (30 April 2014) External Definitions revision number: 4.5 (1 March 2011)

 

Hopefully these SAP results mean something to you Dave.

On the face of it that should be a pretty energy efficient house.  But see if you can do that "turn half the house off" test for say 24 hours?

 

5671kWh of heating, which you will only need for 6 months of the year, is about 31kWh per day average.  A very rough assumption is in the coldest time it will need twice that (and a lot less at the start and end of the heating season) so say 62kWh on a cold day.

 

It's a 7kW HP so will take just under 9 hours to deliver 62kWh of heat running continuously.  How long have you got it set to run for at the moment?  is it as simple as not long enough?

 

Remember also a HP will only do DHW or heating, and it is probably spending an hour a day for DHW so you want to be looking at it to be on for longer.

 

Ours is set to come on at 6AM and off at 9PM  During the day the room thermostats will turn it off once up to room temperature so it won't normally run all day but it could if needed.

[Rich123]

The altherma set up is a bit tricky and requires a number of dip switches to be set .

You should have a commissioning report as this https://www.daikin.co.uk/content/dam/dauk/document-library/Warranty/Daikin UK Commissioning Report.pdf

ive had numerous issues with these not being set up correctly, so that’s the first thing I’d check.

Thats the first thing , as there are priority settings that can effect the operation.

I assume it has an electric boost in the cylinder as 48 C should be boosted say once a week for anti legionella.

SAP is not a designers tool , it’s an energy assessment and I would not rely on the figures as it looks a heat balance not heat loss.

ie it includes gains from lighting , cylinder heat loss, pump heat emissions etc.

Many houses will use double the energy in the assessment !

[DOIGAN]

Hi Rich123,

 

Is this the report you mean?

 

CC-00042462-U (1).pdf

 

 

I usually run a disinfectant cycle once a month at 60 degrees, is that not enough?

 

[DOIGAN]

21 minutes ago, ProDave said:

On the face of it that should be a pretty energy efficient house.  But see if you can do that "turn half the house off" test for say 24 hours?

 

5671kWh of heating, which you will only need for 6 months of the year, is about 31kWh per day average.  A very rough assumption is in the coldest time it will need twice that (and a lot less at the start and end of the heating season) so say 62kWh on a cold day.

 

It's a 7kW HP so will take just under 9 hours to deliver 62kWh of heat running continuously.  How long have you got it set to run for at the moment?  is it as simple as not long enough?

 

Remember also a HP will only do DHW or heating, and it is probably spending an hour a day for DHW so you want to be looking at it to be on for longer.

 

Ours is set to come on at 6AM and off at 9PM  During the day the room thermostats will turn it off once up to room temperature so it won't normally run all day but it could if needed.

Hi Dave,

 

Sorry but when you say 62kw/h is that not extreme? That would cost me £10 a day just for heating. Or are you assuming a CoP of 3.14 where it would generate 62 but use 20kw/h?

Unfortunately my controller does not show energy produced only used.

 

My heating is on for at least 12 per day every day.

[SteamyTea]

52 minutes ago, DOIGAN said:

7kw/h

Ahhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh

Edited January 10, 2021 by SteamyTea

[ProDave]

21 minutes ago, DOIGAN said:

Hi Dave,

 

Sorry but when you say 62kw/h is that not extreme? That would cost me £10 a day just for heating. Or are you assuming a CoP of 3.14 where it would generate 62 but use 20kw/h?

Unfortunately my controller does not show energy produced only used.

 

My heating is on for at least 12 per day every day.

Yes that's right, 62kWh of heat using perhaps 20kWh of electricity, costing perhaps just over £3 per day at the coldest time.

 

What are your actual winter electricity bills (which will include everything else you use as well as heating)

[DOIGAN]

18 minutes ago, ProDave said:

Yes that's right, 62kWh of heat using perhaps 20kWh of electricity, costing perhaps just over £3 per day at the coldest time.

 

What are your actual winter electricity bills (which will include everything else you use as well as heating)

Used 20kw/h today so far, averaging about 25 but we use the wood burner most days to heat the house, pretty sure the system could be on for 24 hours and would feel the same.

[Rich123]

On 10/01/2021 at 12:31, DOIGAN said:

Hi Rich123,

 

Is this the report you mean?

 

CC-00042462-U (1).pdf 179.77 kB · 3 downloads

 

 

I usually run a disinfectant cycle once a month at 60 degrees, is that not enough?

 

Depends on your attitude, ideally weekly but the risk is actually pretty low according to tests I’ve seen. But compliance with anti legionella advice would be more often.

I can’t open the report but I would suspect it is .

[DOIGAN]

On 10/01/2021 at 11:33, ProDave said:

Then that sounds like the ASHP may be too small for the house if it is failing to heat the UFH up to the set temperature.

 

To test that theory, if you are not using all the rooms, turn the room thermostats down in some rooms so you are say heating only half the house and see if it then reaches the set temperature.

 

How big is the house?  What levels of insulation? Do you have any heat calculations e.g SAP? what size is the HP?

Been doing what you suggested, it appears that if I only try and heat 4 rooms my system can maintain about 35 degree LWT, this drops to mid 20's if any more zone valves open, flow rate is about 23l/min. Is this normal? Would have thought that the system would have the capacity to supply the higher heat to all rooms.

[ProDave]

4 minutes ago, DOIGAN said:

Been doing what you suggested, it appears that if I only try and heat 4 rooms my system can maintain about 35 degree LWT, this drops to mid 20's if any more zone valves open, flow rate is about 23l/min. Is this normal? Would have thought that the system would have the capacity to supply the higher heat to all rooms.

That does indeed seem to suggest in this cold spell you ASHP can't keep up with demand.  Not a lot you can do, at least not a lot that is cheap.

[DOIGAN]

Thought you might say something like that. This was my assessment too, we did not install the system in was in the house when we bought it, I presume by an expensive fix you mean a larger ashp?

[TonyT]

Reduce the heating demand, so insulate more of the house.

[ProDave]

Yes the expensive fix is a larger ASHP.  The alternative is some additional heating to supliment the ASHP in very cold weather.

[DOIGAN]

21 hours ago, ProDave said:

Yes the expensive fix is a larger ASHP.  The alternative is some additional heating to supliment the ASHP in very cold weather.

We unfortunately have to use the wood burner ?

[newhouse87]

Sorry to hijack thread, can anybody tell me how i can see my flow and return temp on daikin low temp altherma. Commissioner guy showed me nothing. All i can see is lwt and dhw tank on main screen.